Abstract

Driving rain is one of the most critical sources of moisture affecting the hygrothermal and durability performance of building envelopes. The estimation of severity in terms of annual driving rain indices using annual and monthly weather data (aaDRI and maDRI respectively) aids towards contemplating potential moisture loads, and hence in the efficient design of buildings in the geographical area of interest. In this study, monthly and annual gridded datasets of wind and rainfall, pertaining to the thirty-year period of 1988-2017 have been used to design a spatially continuous driving rain map for India at 0.5°×0.5°(lat./long.) resolution. The observations reveal that the use of annually averaged data leads to underestimation of the driving rain severity thereby highlighting the inefficiency of a coarser temporal scale. A linear relationship has subsequently been developed to enable refinement of aaDRI into maDRI. The analysis of the monthly driving rain map reveals that the entire western coastal belt and a few regions in the north-eastern part of the country observe high to severe exposure conditions. Furthermore, a trend analysis of the yearly driving rain index values reveals statistically significant decreasing trends over the northern and eastern regions of the country, whereas increasing trends in the shielded regions surrounding central India is observed.